Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
  • F01K7/00—Steam engine plants characterised by the use of specific types of engine; Plants or engines characterised by their use of special steam systems, cycles or processes; Control means specially adapted for such systems, cycles or processes; Use of withdrawn or exhaust steam for feed-water heating
  • F01K7/32—Steam engine plants characterised by the use of specific types of engine; Plants or engines characterised by their use of special steam systems, cycles or processes; Control means specially adapted for such systems, cycles or processes; Use of withdrawn or exhaust steam for feed-water heating the engines using steam of critical or overcritical pressure
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
  • F01K3/00—Plants characterised by the use of steam or heat accumulators, or intermediate steam heaters, therein
  • F01K3/02—Use of accumulators and specific engine types; Control thereof

Definitions

• the invention relates to a cycle process for a heat engine with external heat and a heat engine with external planteuhr, which operates according to the inventive cycle. Specifically, the invention relates to supercritical cycle processes and, furthermore, to heat engines designed with isothermal expansion with or without phase change.
• the currently used heat engines in the lower power range up to 150kW mainly use hot gas processes without phase transformation with internal or external heat supply, whereby the maximum working pressure is usually below 150 bar.
• the Rankine process as a high-pressure process with phase transformation is now almost exclusively used in large multi-stage water or ORC steam turbines in the upper power range.
• Hot gas process with internal combustion very good heat input at high speed, high compression work, no recuperability, 5 high cooling losses, high pressure and temperature difference, wear and corrosion very high (for example internal combustion engines);
• Hot gas process with external combustion poor heat input therefore high heater temperatures at high speeds from 300 to 3500 rpm, little or no compaction work, good recuperability, low cooling losses, mean pressure and temperature difference, wear and corrosion low, sealing problems of the Working medium (eg Stirling engines, gas turbines);
• Working medium eg Stirling engines, gas turbines
• the patent US 3 237 403A describes a supercritical cycle with phase transformation.
• C02 is proposed for turbines with isentropic expansion and waste heat recuperation via a countercurrent heat exchanger. Due to the internal cooling of the working medium after isentropic expansion, only a portion of the heat supplied can be recuperated. The return of the working medium and the pressure build-up happens under energy losses classically over condenser and boiler feed pump. In sum, therefore, only small improvements in expansion rate and energy efficiency can be achieved.
• Patent DE 10 2008 04 28 28 B4 uses liquid pistons for a classic Stirling cycle.
• the alternating immersion in a structured heat exchanger improves the isothermal heat transfer during compression and expansion and small dead spaces. Recuperation takes place in the gas area via countercurrent heat exchangers.
• the fluid seal and energy conversion requires a heat-resistant fluid at very high gas temperatures and appropriate fluid fittings.
• the patent application DE 34 27 219 AI relates to a supercritical steam engine cycle process in which serving as a working, in the supercritical temperature range and pressure range directly recovered from the liquid phase, at constant supercritical pressure further superheated hot or cold gas supplied to a gas turbine in the same up close expands adiabatically or polytropically to the critical point of the working substance and the cooling of the gas is taken to 5 before its complete liquefaction by means of a heat pump and / or expansion chamber.
• the patent application US 2013/0151576 AI relates to a system with a closed cycle for waste heat utilization, comprising a heat exchanger, the heat from an external Transferring heat source to a working medium, an expansion machine in fluid communication with an outlet of the heat exchanger and configured to expand the working medium and produce mechanical energy, a recuperator fluidly connected to an outlet of the expansion machine, and configured; Removing heat from the working medium, a condensing unit in fluid communication with an outlet of the recuperator and configured to condense the working medium, and a pump in fluid communication with an outlet of the condensing unit and configured to form the condensed working medium to pump back into the recuperator, wherein the recuperator is in fluid communication with the heat exchanger, so that the working fluid follows a closed path.
• the patent US 8,783,034 B2 relates to a thermodynamic cycle for hot days, in which a pump drives a working fluid through a heat exchanger, where it is heated and is expanded by a turbine. Thereafter, it is cooled to ambient temperature and liquefied by a multi-stage compressor with Eisenkühiung.
• the patent US 8,006,496 B2 relates to a motor with working fluid in a closed circuit with at least one pump for the pressure build-up in the fluid and for the further pressure build-up during the recuperative heat absorption, and a heater to the fluid over its critical temperature to its max. To bring working temperature.
• the output is followed by an expander for mechanical energy conversion with reflux to the recuperative heat exchanger.
• the patent US 4 077 214 A relates to a heat engine for condensable wet steam as a working medium, consisting of cylinder and a piston. In the upper dead space, the heat input is tuned to a certain minimum possible dead space volume.
• the object of the invention is to improve the thermodynamic efficiency over the cycle while avoiding the main disadvantages and taking advantage of certain advantages of the above-mentioned methods.
• the aim is also to increase longevity, low production costs and flexibility with regard to the heat source.
• a major problem of high-compression Stirling engines is also the sealing of the working fluid to the outside and the subsequent Energyiückkopiung.
• a supercritical cycle with phase transformation is provided for heat engines with working space-external heat supply, whereby a working medium in a working space under working space-external heat supply is expanded supercritically at a predetermined upper working temperature
• the external heat energy supply during the isothermal expansion and all process steps except the isothermal expansion are made possible by a recuperation of the heat energy for using the heat buffer device.
• the difference between the predetermined upper working temperature and the predetermined lower working temperature is greater than 150 Kelvin, in particular several 100 Kelvin, and wherein the lower working pressure is at least above the critical pressure of the working medium and the difference between the upper working pressure and the lower Working pressure is more than 50 bar, in particular several hundred bar and wherein the expansion rate is more than seven times the liquefied working volume.
• the invention comprises a heat engine with external heat supply and hydraulic energy extraction for carrying out a thermodynamic cyclic process with isothermal expansion, isochoric pressure buildup and isobaric work volume expansion and work volume contraction, for carrying out the cycle according to the invention, comprising: at least one working cylinder and one contraction cylinder, wherein in the working cylinder a working piston is arranged to be movable to and fro, which defines a working space in which a working medium is periodically contractible and expandable,
• a control piston is arranged to reciprocate, wherein in the contraction cylinder further a heat storage device is arranged, wherein the heat storage device stores heat energy during the work volume contraction and provides the stored heat energy for the subsequent isochoric pressure build-up and further isobaric expansion,
• a heating device for supplying working space-external heat is arranged, by means of which the working fluid in the cylinder is heated isothermally, wherein in the working cylinder further comprises a thermally conductive oscillator piston is arranged, which is movable in the expanding working space of the working cylinder and forth for transmitting external Heat is designed via the cylinder wall into the working medium, wherein the oscillator piston has openings in its axial direction 5, which are dimensioned so that the working fluid is forced through turbulent and swirled after exiting the oscillator piston in the working cylinder.
• hydraulic areas are provided which are under the same pressure as the working fluid in the working space and transmit a volume change of the working fluid to the outside of the working space and ensure additional hermetic sealing of the working space.
• the heat engine may comprise: a master drive in the form of a cam or a linear actuator for actuating the control piston and a slave drive in the form of a linear or linear actuator, which is synchronized with the master drive and is axially connected to the oscillator piston, and wherein the master drive and the slave drive for the purpose of differential pressure compensation are either completely or partially within the hydraulic ranges.
• the heat engine may have: Each a pressure chamber externally driven magnetic coupling, which is magnetically coupled to the oscillator piston from the outside, and a pressure-externally driven magnetic coupling, which is magnetically coupled to the control piston from the outside displaceable.
• the heat engine may comprise a static regenerator and heat sink or a movable regenerator connected to the control piston.
• the contraction cylinder can be dimensioned such that it can accommodate the entire liquefied working medium.
• cooling devices can be arranged on the contraction cylinder.
• the working piston can be designed as an extended free piston and medium separating piston between the working space and the hydraulic area, the piston piston tions on the side of the cold pole outside the hot working space, wherein the cold pole can be provided with a cooling device.
• control piston can be designed either with piston seals as a media separating piston between the cold region of the working chamber and the hydraulic region or within the cold region of the working medium as a displacer without piston seals.
• the heater can be used as a combustion head with heat exchanger ribs or formed as an insulated heating sleeve, which is filled with a heat transfer medium.
• the entire machine can be designed as a low-speed rotor with a high maximum working pressure and a high expansion rate.
• the invention relates to a cyclic process that allows almost complete conversion of heat into mechanical energy and implement the reciprocating device to this.
• This completely supercritical circular process with isothermal expansion allows a very high rate of recuperation despite phase change, since every change in the energy of the working medium in the upper and lower isobars is associated with a non-latent temperature change at about the same level.
• the isothermal expansion also allows the greatest possible expansion ratio of the working medium in the context of this cycle. It exceeds that of pure, externally heated hot gas engines by a maximum of 1: 3 by a multiple. Since the pressure is built up (see point 3 to point 4 in Fig. 1), also eliminates the mechanical Vorverdichtungsarbeit.
• the device according to the invention is provided with a hydaulischen energy conversion.
• the isothermal expansion (1-2) of the gaseous working medium is realized by supplying heat through the cylinder wall and an oscillator piston with turbulator slots, which oscillates linearly in the increasing working space.
• the working piston is designed as a hollow free piston with sealing rings at the cold end and follows, as well as the oscillator piston drive, the stroke of the control piston, which is driven by the external master drive. All external piston actuators are operated with virtually no force with hydraulic pressure equalization and require only low mechanical energy input due to the process. Due to the elongated design, the device has a high thermal resistance in the direction of the hydraulic pressure chambers or cold poles and requires process-related relatively little external cooling.
• the invention is associated with the following priorities and advantages: Flexibility in the selection of the heat carrier and high efficiency.
• the machine according to the invention Due to the supercritical cyclic process, the machine according to the invention (according to FIG. 3) uses a working medium with an upper working pressure of several 100 bar, high specific density and therefore high thermal conductivity. Since this cycle always runs above the critical pressure of the wet steam curve, all heat exchanges are non-latent, i. associated with a temperature gradient. This allows in principle the heat recovery in the area of isobaric expansion or contraction in a countercurrent heat exchanger or recuperator and is already utilized in hot gas processes. However, the special feature of the supercritical cycle process is that at the same time a phase transformation takes place, provided that the lowest process temperature Tu is below the critical temperature of the working medium.
• the two-cylinder variant with 180 ° phase offset is chosen to achieve the most uniform possible hydraulic energy extraction.
• the number of cylinders can be configured from one to several, with a pressure accumulator and a leak oil pump should be used to puêtropin the lower working pressure.
• hydraulic components incl. Hydraulic motor, hydraulic seals, valves and hoses series parts from 220 to 700 bar can be used.
• the system is designed to be stretched to maximize thermal resistance (similar to ohmic resistance) from the hot working zone to the cold zones at both ends of the cylinder, thus minimizing cooling losses.
• Fig.1 idealized supercritical (T-p-v-p) cycle after the machine of the invention operates on the example of the log-ph diagram of CO2 as a working medium;
• FIG. 2 shows a hydraulic circuit of the machine in a double-cylinder arrangement for energy output
• Fig.3 Two working cylinders in the preferred design with 180 ° phase offset and mechanical control
• FIG. 4 Structure as in FIG. 3 with control via internal differential pressure compensated linear actuators
• Fig.5 Design variant with magnetically coupled external servo drive with differential pressure compensation and the control piston as a plunger without media separation;
• Fig.6 Off-time control curves of the 3 actuators.
• Fig. 1 is an idealized log-ph diagram of the supercritical isothermal (Tp-vp) cycle according to which this system operates in accordance with the invention.
• the idealized cycle runs around to the right through the vertices 1 to 4 using the example of the working medium C02. It is completely above the critical pressure and just below the critical temperature of the working medium to achieve a phase change from the liquid to the supercritical gas state.
• the temperature range of the heat source is therefore crucial for the selection of the working medium (eg CO 2, NH 3, other refrigerants, water, etc.). Due to the phase change and the isothermal external heat supply, an expansion ratio> 10 can be achieved despite the high process pressures.
• the isobaric expansion is carried out by further heat supply from the recuperator (or a countercurrent heat exchanger with heat removal from point 2 to point 3).
• the constant upper working pressure po during this process is independent of the working medium and is determined solely by the generator counter-moment. The higher the difference between the upper and lower working pressure, the higher the turnover.
• Fig.2 the circuit diagram for the hydraulic energy conversion of the translation is shown in a continuous rotation with translation to generator speed.
• Generator 20 is connected via a coupling with hydraulic motor 22 and flywheel 21.
• the high pressure side HD is alternately filled by the check valves 25.1 via the respective high pressure lines 26.1 of the working cylinder. Possible pressure peaks are smoothed with the pressure control valve 24.1.
• the low pressure side ND allows the oil return from the hydraulic motor 22 in the working cylinder via the check valves 25.2 and the respective low pressure lines 26.2 of the working cylinder.
• the pressure level on the low pressure side ND is maintained with the pressure regulating valve 24. 2, the pressure accumulator 28 and the leak oil pump 29.
• the lines 27 are bypass lines to allow pressure equalization between both ends of the working cylinder.
• the preferred construction is shown in two-cylinder arrangement with 180 ° phase offset with mechanical control, as at burner temperatures up to 1200 ° C for the supercritical cycle according to claim 1-4 (Fig.l) but also with real hot gas (eg Air, helium, etc.) can be used with the same process flow.
• real hot gas eg Air, helium, etc.
• the duty cycle in the upper cylinder starts with the isothermal expansion stroke of the working piston 3 after the control piston 1 has been extended to the maximum of the common master cam drive lb-ld.
• the working piston 3 is a differential free piston, which always strives for the two-sided pressure balance and is moved by the slightest pressure differences. It is designed as an insulating hollow piston with inner tube and seals near the cold pole at HR1.
• the gaseous working medium in the working chamber AR is reheated uniformly by means of the oscillating piston 5, which has been heated via the cylinder wall 4. This oscillates during expansion with increasing amplitude between the solid liquefaction cylinder 2 and the working piston 3 back and forth.
• the respective oscillator piston is moved by a linear slave servo drive 5.b, which is synchronized with the master drive lb-ld.
• the oscillator piston 5 has circumferentially in the axial direction of fine slits through which the working gas is pushed through turbulent, and then swirled. This ensures that whenever possible every molecule of the working gas with the hot oscillating piston 5 and the cylinder wall 4 comes into contact again during the expansion and is thus reheated.
• the working pressure decreases continuously, while the temperature of the working gas and the surrounding components around the working space AR by the external heat supply remain approximately constant. As a result, the formation of alternating voltage cracks and temperature fluctuations in this highly stressed cylinder region 4 is prevented.
• the back contraction or re-liquefaction in AR takes place continuously and simultaneously with the retraction movement of the control piston 1 over the entire path.
• the oscillator piston rests against the working piston 3 and is passively moved by it.
• the remindkontratation or re-liquefaction is isobaric, the lower system pressure pu via a pressure control valve, a leak oil pump and a pressure accumulator is kept stable. Almost all of the heat removal can take place non-latently via the regenerator 7 in accordance with the cycle in FIG.
• the advantage of a regenerator over a countercurrent heat exchanger is that it can be used e.g. Made of pressure-stable fine steel wire and therefore allows a maximum surface and turbulence of the working medium even at the highest working pressures.
• the regenerator can be over-dimensioned with regard to the heat storage capacity per stroke in order to ensure the greatest possible heat exchange.
• Heat sink 6, contraction cylinder 2 and hydraulic range HR1 are adequately cooled by a water-cooling jacket or air cooler 8.
• the optional water cooling jacket or air cooler 9 should also prevent the heating in the direction of HR2. This heat dissipation depends primarily on the thermal resistance of the thermal bridges from AR to HR1 and HR2 and is not (as usual) due to the cycle. It thus also serves to maintain the temperature gradient between the hot pole in AR and the cold poles in HR1 and HR2 and requires comparatively small amounts of cooling water.
• the working medium can be used for cooling and preheated fresh water or heating water.
• the following isochore pressure build-up is instantaneously realized by pushing out the control piston of a small subset of the contracted or liquid working medium via recuperative heat supply.
• the associated successive pressure equalization is only possible in cyclic work processes and not in continuous processes (for example, turbines with boiler feed pump). It reduces the work required to build up the working pressure on the back pressure of the working medium. Because of the external rod drive 1.a comes here still the differential piston work (stroke x rod cross-section) of the control piston added.
• the isolated combustion chamber 10 has the task to guide the fuel gases so that they transfer the heat of the fuel gases optimally to the cylinder ribs of the working cylinder 4.
• the still hot exhaust gases (just above To) are then used via a separate countercurrent heat exchanger either for burner air preheating or heating of heating or service water.
• Both the control pistons and the oscillator pistons are moved by means of linear drives or hydraulic cylinders. They are located within the hydraulic fluid in HR 1 and HR 2 in complete differential pressure compensation.
• the drive motors can also be arranged outside the pressure chamber HR 1 and HR 2 via rotary feedthroughs.
• the mechanical structure is simpler and less subject to wear. This version is therefore useful for larger, cost-intensive systems, where it depends primarily on durability and reliability.
• FIG. 5 shows a modification of the design according to FIG. 3, which is particularly useful for low-temperature applications.
• the entire system is hermetically sealed and the actuators are moved with magnetic couplings and differential pressure compensation.
• the control piston is designed here as a purely sealless displacer 1 with magnet ring 1.a and recuperator 1.c as an assembly. He is completely inside the working medium and is moved over the magnetic ring 1.b.
• the use of low temperature may require a working fluid whose critical temperature is below ambient temperature.
• the liquefaction temperature around the displacer 1 must be at least 10 K below this critical temperature. This can be achieved, for example, via a small external heat pump. Since hydraulic oil becomes viscous at these degrees of coldness or falls below its pour point and seals become brittle, this version has been equipped with a sealless displacer 1. However, the thermal resistance is lower here compared to the version in FIG. 3, which results in higher cooling losses in the region HR1.
• insulated heating sleeves 4 with heating water or heat transfer oil.
• the oscillator piston 5 is here moved with a hollow magnet rod 5.a via a magnet ring 5.b.
• the hydraulic fluid in HR2 can flow around and around the magnet rod, ensuring full pressure balance and minimal flow resistance. The cooling on this page can be omitted, provided that the working temperature of the working medium does not exceed the limit temperature of the hydraulic oil in the room HR2 inadmissible.
• the entire arrangement is to be isolated as best as possible (FIGS. 10 and 11), since the cold pole in the area HR1 may be below, and the hot pole in the working space AR above the ambient temperature, and these will be adversely affected in both cases.
• control points 1 to 4 relate to the cycle process according to the invention according to FIG. 1, but can also be used for a normal hot gas process, whereby the working pressure and the expansion rate should be lower here.

Landscapes

• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Engine Equipment That Uses Special Cycles (AREA)

Priority Applications (3)

Applications Claiming Priority (2)

Publications (1)

Family

ID=56026619

Family Applications (1)

Country Status (4)

Cited By (2)

Families Citing this family (1)

Citations (13)

• 2015
  • 2015-04-17 DE DE102015105878.2A patent/DE102015105878B3/de active Active
• 2016
  • 2016-04-08 CN CN201680012929.3A patent/CN107636261B/zh active Active
  • 2016-04-08 WO PCT/DE2016/100166 patent/WO2016165687A1/de active Application Filing
  • 2016-04-08 EP EP16723930.0A patent/EP3320189B1/de active Active
  • 2016-04-08 DE DE112016001781.2T patent/DE112016001781A5/de not_active Withdrawn

Patent Citations (13)

Non-Patent Citations (2)

Also Published As

Similar Documents

Legal Events